fix: expand ${env:VAR} placeholders in settings

[jdillon]

Summary

• Add resolveEnvVariables() utility that expands ${env:VAR} placeholders using process.env, matching VS Code's variable syntax from launch.json/tasks.json
• Apply expansion to beads.userId and beads.pathToBd settings so users can use ${env:USER} or custom env vars
• Missing env vars resolve to empty string (don't leave placeholder literal)
• Add Jest test infrastructure (jest.config.js with ts-jest) and 8 tests covering all edge cases
• Update setting descriptions in package.json to document ${env:VAR} support

Fixes #60

Test plan

• Set beads.userId to ${env:USER} — verify "Assign to me" uses actual username
• Set beads.userId to ${env:NONEXISTENT} — verify fallback to $USER
• Set beads.pathToBd to ${env:HOME}/bin/bd — verify CLI resolves correctly
• Set beads.userId to a plain string — verify no regression
• Run bun run test — all 8 tests pass

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • beads.userId and beads.pathToBd configuration settings now support environment variable expansion using ${env:VAR} placeholder syntax. Missing environment variables are substituted with empty strings.

• Documentation

  • Updated configuration property descriptions to document the environment variable placeholder expansion capability with usage examples.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR implements environment variable placeholder expansion for beads.userId and beads.pathToBd configuration settings. A new utility function resolveEnvVariables scans strings for VS Code-style ${env:VAR} placeholders and replaces them with corresponding environment variable values. The feature is integrated into two configuration-reading locations, accompanied by comprehensive tests and documentation updates.

Changes

Cohort / File(s)	Summary
Documentation & Configuration CHANGELOG.md, package.json	Added changelog entry and updated VS Code configuration property descriptions to document support for ${env:VAR} placeholder expansion in beads.userId and beads.pathToBd.
Core Utility Implementation src/utils/resolve-env-variables.ts	New exported utility function that processes strings to expand ${env:VAR} placeholders using process.env values, replacing undefined variables with empty strings.
Feature Integration src/backend/BeadsProjectManager.ts, src/providers/BaseViewProvider.ts	Integrated resolveEnvVariables() to preprocess configured values before use: getBdPath() processes the BD path, and initializeView() processes the user ID setting.
Testing & Jest Setup jest.config.js, src/utils/__tests__/resolve-env-variables.test.ts	Added Jest configuration file and comprehensive test suite validating placeholder expansion, multiple placeholders, missing variables, malformed inputs, and edge cases.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A carrot path, a name so true,
With ${env:VAR} magic through and through,
The beads now know where home resides,
Environment secrets, no longer hides! 🌿

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: adding environment variable placeholder expansion to settings.
Linked Issues check	✅ Passed	The PR fully addresses issue #60 by implementing ${env:VAR} expansion in beads.userId and beads.pathToBd with proper tests and documentation.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing env placeholder expansion. The Jest config and test infrastructure support the core feature implementation.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/userid-variable-expansion

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[coderabbitai]

🧹 Nitpick comments (1)

jest.config.js (1)

1-9: Consider adding ESLint environment directive for CommonJS.

The static analysis flagged 'module' is not defined because this CommonJS config file runs in a context where ESLint expects ESM. This doesn't affect functionality but could be silenced.

🔧 Optional fix to silence ESLint

 /** `@type` {import('jest').Config} */
+/* eslint-env node */
 module.exports = {

Alternatively, you could rename to jest.config.cjs to make the CommonJS format explicit, but jest.config.js is the conventional name.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@jest.config.js` around lines 1 - 9, The ESLint warning is because the
CommonJS usage (module.exports) in jest.config.js is being linted as ESM; add an
ESLint environment directive for CommonJS at the top of the file (e.g., add a
line declaring the commonjs env) so ESLint recognizes module.exports, or
alternatively rename the file to jest.config.cjs to make the CommonJS format
explicit; ensure the change targets the module.exports export in this file.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@jest.config.js`:
- Around line 1-9: The ESLint warning is because the CommonJS usage
(module.exports) in jest.config.js is being linted as ESM; add an ESLint
environment directive for CommonJS at the top of the file (e.g., add a line
declaring the commonjs env) so ESLint recognizes module.exports, or
alternatively rename the file to jest.config.cjs to make the CommonJS format
explicit; ensure the change targets the module.exports export in this file.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 88d5cd05-ca0b-4131-80a1-c00180b1b575

📥 Commits

Reviewing files that changed from the base of the PR and between 797ef48 and e3b8659.

📒 Files selected for processing (7)

• CHANGELOG.md
• jest.config.js
• package.json
• src/backend/BeadsProjectManager.ts
• src/providers/BaseViewProvider.ts
• src/utils/__tests__/resolve-env-variables.test.ts
• src/utils/resolve-env-variables.ts